Battery cell and battery pack

Abstract

The application relates to the technical field of batteries, in particular to a battery monomer and a battery pack. The application provides a battery monomer, which comprises a shell, a first electrode terminal, a first electrode assembly and a first tab part. The shell is used for containing the first electrode assembly, and the shell has a first wall. The first electrode terminal is arranged on the first wall. The first tab part comprises at least two first tab pieces, the first tab pieces extend from at least one end of the first electrode assembly, and the first tab part is electrically connected with the first electrode terminal. First and second welding marks are arranged on the first tab part. According to the projection on the large surface of the first tab part, the orthographic projection of the second welding mark falls into the orthographic projection of the first welding mark, and the second welding mark is used for welding the first electrode terminal and the first tab part. The roughness of the second welding mark is greater than that of the first welding mark. The technical effect of improving the welding strength between the tab and the electrode terminal is achieved.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of batteries, in particular to a battery monomer and a battery pack. BACKGROUND

[0002] In the related art, a battery comprises an electrode assembly and a cover plate assembly, the cover plate assembly is connected with the tab of the electrode assembly, and the tab and the cover plate assembly are welded by torque. Since there is a gap between the tabs, after the ultrasonic welding equipment completes the surface compression welding of the tabs, the edges of the welding marks are raised to form convexities, which can easily cause the tearing of the pole piece and the occurrence of false welding, thereby affecting the reliability of the connection between the pole and the tab. SUMMARY

[0003] The application provides a battery monomer and a battery pack, which achieve the technical effect of improving the welding strength between the tab and the electrode terminal.

[0004] In order to achieve the above-mentioned purpose, the main technical scheme adopted by the application comprises:

[0005] The application provides a battery monomer, which comprises a shell, a first electrode terminal, a first electrode assembly and a first tab part. The shell is used for accommodating the first electrode assembly, and the shell has a first wall. The first electrode terminal is arranged on the first wall. The first tab part comprises at least two first tab pieces, the first tab pieces extend from at least one end of the first electrode assembly, and the first tab part is electrically connected with the first electrode terminal. The first tab part is provided with a first welding mark and a second welding mark. Along the projection on the large surface of the first tab part, the orthographic projection of the second welding mark falls into the orthographic projection of the first welding mark, and the second welding mark is used for welding the first electrode terminal and the first tab part. The roughness of the second welding mark is greater than the roughness of the first welding mark.

[0006] The battery monomer provided by the application is characterized in that the first tab pieces extend from at least one end of the first electrode assembly, the at least two first tab pieces are stacked and pre-welded and compressed to form the first welding mark, so as to reduce the gap between the first tab pieces and also reduce the raising or convexity of the welding edge of the first tab pieces. Then, the first tab part and the first electrode terminal are welded at the first welding mark to form the second welding mark. Along the projection on the large surface of the first tab part, the orthographic projection of the second welding mark falls into the orthographic projection of the first welding mark, which means that the second welding mark is located in the first welding mark area, thereby improving the welding strength between the first tab part and the first electrode terminal.

[0007] That is, when connecting the first electrode assembly and the first electrode terminal, first, one end of the first tab portion is connected with the first electrode assembly, the other end of the first tab portion is overlapped and pre-welding is performed to form a first welding mark, and then welding is performed on the first tab portion and the first electrode terminal in the area of the first welding mark to form a second welding mark. That is, pre-welding is performed on the first tab portion so that each metal sheet of the first tab portion is combined together, and the structural strength of the first tab portion is improved by pre-welding, so that when welding is performed on the first tab portion and the first electrode terminal again, even if the welding energy is relatively large, the structural strength of the first tab portion is enhanced due to the presence of the first welding mark, so that when welding the first tab portion and the first electrode terminal, the damage to the first tab portion can be reduced.

[0008] In order to sufficiently weld between the first tab portion and the first electrode terminal and improve the welding strength, the roughness of the second welding mark needs to be greater than the roughness of the first welding mark. If the roughness of the first welding mark is too large, the second welding mark cannot fully contact each first tab sheet when the first tab portion and the first electrode terminal are welded, and the problem of false welding is prone to occur, thereby reducing the welding strength between the first tab portion and the first electrode terminal.

[0009] The application also provides a battery monomer, comprising a shell, a first electrode terminal, a first electrode assembly, a first tab portion, a second electrode assembly and a second tab portion, the shell is used for accommodating the first electrode assembly and the second electrode assembly, the shell has a first wall; the first electrode terminal is arranged on the first wall; the first tab portion comprises at least two first tab sheets, the first tab sheet extends from at least one end of the first electrode assembly, the first tab portion is electrically connected with the first electrode terminal; the second tab portion comprises at least two second tab sheets, the second tab sheet extends from at least one end of the second electrode assembly, the second tab portion is electrically connected with the first electrode terminal; the first tab portion and the second tab portion are overlapped and welded to form a first welding mark and a second welding mark, along the projection on the large surface of the first tab portion or the second tab portion, the orthographic projection of the second welding mark falls into the orthographic projection of the first welding mark, the second welding mark is used for welding at least one of the first tab portion and the second tab portion with the first electrode terminal; wherein the roughness of the second welding mark is greater than the roughness of the first welding mark.

[0010] The first tab part and the second tab part are overlapped and welded to form the first welding mark, and then the first tab part and the second tab part are overlapped and welded to form the first welding mark, and then the first tab part and the second tab part are welded with the first electrode terminal in the first welding mark area to form the second welding mark. Since the thickness of the overlapped first tab part and second tab part is relatively thick, in order to prevent false welding between the first tab part, the second tab part and the first electrode terminal, it is necessary to increase the depth of the second welding mark, that is, to increase the roughness of the second welding mark, so that the first tab part and the second tab part are in full contact with the first electrode terminal, thereby improving the connection strength between the first tab part, the second tab part and the first electrode terminal.

[0011] The application also provides a battery pack comprising the battery monomer of any one of the above embodiments.

[0012] In the battery pack provided by the embodiments of the application, the first tab part is first pre-welded to form the first welding mark, and then the first tab part is welded with the first electrode terminal in the area of the first welding mark to form the second welding mark, thereby reducing the probability of warping or tearing of the first tab part outside the first welding mark area. The roughness of the first welding mark is less than the roughness of the second welding mark, so that the first tab part is in full contact with the first electrode terminal, thereby improving the connection strength between the first tab part and the first electrode terminal and further improving the structural stability of the battery pack. BRIEF DESCRIPTION OF DRAWINGS

[0013] In order to more clearly illustrate the technical solutions in the specific embodiments of the application or the prior art, the following will briefly introduce the drawings needed to be used in the description of the specific embodiments or the prior art. Obviously, the drawings described below are some embodiments of the application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0014] Figure 1 It is a structural schematic diagram of the battery monomer of the application;

[0015] Figure 2 It is a partial structural schematic diagram of the battery monomer in one embodiment of the application;

[0016] Figure 3 It is a projection area schematic diagram of the first welding mark and the second welding mark along the projection on the large surface of the first tab part in the application;

[0017] Figure 4 It is a partial structural schematic diagram of the battery monomer in another embodiment of the application;

[0018] Figure 5 A partial structure diagram of a battery cell in another embodiment of the present application;

[0019] Figure 6 A partial structure diagram of a battery cell in another embodiment of the present application; Figure 5 A schematic diagram of the projected areas of the first, second, third and fourth solder prints along the projection on the large surface of the first tab portion;

[0020] Figure 7 A structure diagram of a first wall in the present application;

[0021] Figure 8 A structure diagram of a first tab portion in the present application.

[0022]

Explanation of Reference Numerals

[0023] 1: outer case; 11: first wall; 12: electrode terminal;

[0024] 2: first electrode assembly;

[0025] 3: first tab portion; 31: first end; 32: second end; 33: first portion; 34: second portion; 35: bent portion;

[0026] 4: first solder print; 41: first edge; 5: second solder print; 51: second edge;

[0027] 6: second electrode assembly;

[0028] 7: second tab portion; 71: third end; 72: fourth end;

[0029] 8: third solder print; 9: fourth solder print. DETAILED DESCRIPTION

[0030] In order to make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described below in connection with the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0031] Unless otherwise defined, all technical and scientific terms used in the application have the same meanings as commonly understood by one of ordinary skill in the art to which this application belongs; the terminology used in the specification herein is for describing particular embodiments only and is not intended to be limiting of the application; the use herein of terms such as "comprise", "comprising", "comprises", "including", "includes" or "contain" or "containing" or "have" or "has" or "having" or "include" or "includes" or "comprising", or "contain" or "containing" or "have" or "has" or "having" or "include" or "includes" or "comprising", or variations thereof, is to be construed as whatever the opposite term as set out herein is intended to express.

[0032] Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the application. The appearances of the phrase "in an embodiment" in various places in the specification are not necessarily all referring to the same embodiment, nor are they necessarily all directed to the same embodiment, or to a single alternative embodiment.

[0033] In the description of the application, it is necessary to explain that, unless otherwise explicitly specified and limited, the terms "mount", "connect", "connection", "attach" should be understood in a broad sense, for example, can be fixedly connected, can be detachably connected, or integrally connected; can be directly connected, or indirectly connected through an intermediate medium, can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the application can be understood according to the specific circumstances.

[0034] The term "and / or" in the application is only to describe the association relationship of the associated objects, which means that there can be three kinds of relationships, for example, A and / or B can represent the existence of A alone, the existence of A and B at the same time, and the existence of B alone. In addition, the character " / " in the application generally represents that the front and rear associated objects have an "or" relationship.

[0035] "Multiple" appearing in the application means more than two (including two), and similarly, "multiple groups" means more than two groups (including two groups), and "multiple pieces" means more than two pieces (including two pieces).

[0036] In the related art, the battery includes an electrode assembly and a cover plate assembly, the cover plate assembly is connected with the tab of the electrode assembly, and the tab and the cover plate assembly are currently welded by torque welding. Since there is a gap between the tabs, after the compression welding is completed, the edge of the welding mark will be raised to form a convex, which is easy to cause the tearing of the tab, and is easy to cause virtual welding, resulting in insufficient welding strength between the tab posts after welding.

[0037] In view of this, with reference to Figure 1 ,Figure 2 and Figure 7 The application provides a battery monomer, which comprises a shell 1, a first electrode terminal 12, a first electrode assembly 2 and a first tab part 3, the shell is used for containing the first electrode assembly 2, the shell 1 has a first wall 11; the first electrode terminal 12 is arranged on the first wall 11; the first tab part 3 comprises at least two first tab pieces, the first tab pieces extend from at least one end of the first electrode assembly 2, the first tab part 3 is electrically connected with the first electrode terminal 12; the first tab part 3 is provided with a first welding mark 4 and a second welding mark 5, along the projection on the large surface of the first tab part 3, the orthographic projection of the second welding mark 5 falls into the orthographic projection of the first welding mark 4, the second welding mark 5 is used for welding the first electrode terminal 12 and the first tab part 3; wherein the roughness of the second welding mark 5 is greater than the roughness of the first welding mark 4.

[0038] The shell is made of metal material and is used for containing the first electrode assembly 2, the shell 1 has a first wall 11, and the first electrode terminal 12 is arranged on the first wall 11. Each first tab part 3 has a first end 31 and a second end 32, the first end 31 of the first tab part 3 is connected with the first electrode assembly 2, and the second end 32 of each first tab part 3 is stacked and welded to form the first welding mark 4, the first welding mark 4 is used for pressing the first tab part 3, the first welding mark 4 is connected with the first electrode terminal 12 to form the second welding mark 5, and the second welding mark 5 is used for welding the first electrode terminal 12 and the first tab part 3; wherein along the stacking direction of the plurality of second ends 32, the projection of the second welding mark 5 falls into the projection of the first welding mark 4, and the roughness of the second welding mark 5 is greater than the roughness of the first welding mark 4.

[0039] The battery monomer provided in the application embodiment, the first end 31 of the first tab part 3 is connected with the first electrode assembly 2, the second end 32 of the first tab part 3 is stacked and pre-welded and pressed to form the first welding mark 4, so that the gap between the plurality of first tab pieces in the first tab part 3 is reduced, and the plurality of first tab piece welding edges can also be reduced or form a convex. Then, the first tab part 3 and the first electrode terminal 12 are welded at the first welding mark 4 to form the second welding mark 5, wherein along the stacking direction of the plurality of second ends 32, the projection of the second welding mark 5 falls into the projection of the first welding mark 4, which means that the second welding mark 5 is located in the region of the first welding mark 4, so that the welding strength between the first tab part 3 and the first electrode terminal 12 is improved.

[0040] That is, when connecting the first electrode assembly 2 and the first electrode terminal 12, first, the first end 31 of the first tab 3 is connected with the first electrode assembly 2, the second end 32 of the first tab 3 is overlapped and pre-welded to form the first weld 4, and then the first tab 3 and the first electrode terminal 12 are welded in the area of the first weld 4 to form the second weld 5. That is, the second end 32 of the first tab 3 is overlapped and pre-welded so that the metal sheets of the first tab 3 are combined together and the structural strength of the first tab 3 is improved by pre-welding, so that when the first tab 3 and the first electrode terminal 12 are welded again, even if the welding energy is relatively large, the structural strength of the first tab 3 is enhanced by the first weld 4, so that when the first tab 3 and the first electrode terminal 12 are welded, the damage to the first tab 3 can be reduced.

[0041] In order to sufficiently weld the first tab 3 and the first electrode terminal 12 and improve the welding strength, the roughness of the second weld 5 needs to be greater than the roughness of the first weld 4. If the roughness of the first weld 4 is too large, the second weld 5 cannot fully contact each first tab sheet when the first tab 3 and the first electrode terminal 12 are welded, which can easily cause the problem of false welding, thereby reducing the welding strength between the first tab 3 and the first electrode terminal 12.

[0042] In this application, the large surface of the first tab 3 is the surface of the first tab 3 after being flattened along the lead-out direction after the first tab 3 is overlapped by a plurality of first tab sheets. Specifically, referring to Figure 8 , the first tab 3 includes a first part 33 connected with the first electrode assembly 2, a second part 34 connected with the first electrode terminal 12, and a bending part 35 connected between the first part 33 and the second part 34, wherein the second part 34 is the large surface of the first tab 3.

[0043] In this application, the first electrode terminal 12 refers to a pole, and the first electrode assembly 2 refers to a cell formed by winding or laminating a stack, which includes a first electrode, a separator, and a second electrode. When the first electrode is a positive electrode, the second electrode is a negative electrode.

[0044] Optionally, the roughness of the second soldering 5 is a1, and the roughness of the first soldering 4 is a2, which satisfies: 5≤a1 / a2≤300, for example, a1 / a2 can be equal to 5, 10, 15, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, or 300, etc. The roughness of the second soldering 5 is greater than the roughness of the first soldering 4, which reduces the problem of false welding between the first tab 3 and the first electrode terminal 12, so as to improve the welding between the first tab 3 and the first electrode terminal 12. However, if the roughness of the second soldering 5 is too large, it is easy to cause the second soldering 5 to pierce the first tab 3.

[0045] Optionally, the roughness of the second soldering 5 satisfies: 300μm≤a1≤3000μm; and the roughness of the first soldering 4 satisfies: 10μm≤a2≤500μm.

[0046] The roughness a1 of the second soldering 5 can be 300μm, 400μm 、 500μm, 600μm, 700μm, 800μm, 1000μm, 1100μm, 1200μm, 1300μm, 1400μm, 1500μm, 1600μm, 1700μm, 1800μm, 1900μm, 2000μm, 2100μm, 2200μm, 2300μm, 2400μm, 2500μm, 2600μm, 2700μm, 2800μm, 2900μm, or 3000μm, etc.

[0047] The roughness a2 of the first soldering 4 can be 10μm, 20μm, 50μm, 80μm, 100μm, 120μm, 150μm, 180μm, 200μm, 220μm, 240μm, 260μm, 280μm, 300μm, 330μm, 340μm, 350μm, 360μm, 380μm, 400μm, 410μm, 420μm, 430μm, 440μm, 450μm, 470μm, 480μm, 490μm, or 500μm, etc.

[0048] Optionally, the first soldering 4 is formed by toothless welding. The second end 32 of the first tab 3 is formed with the first soldering 4 by toothless welding, so as to improve the flatness of the surface of the first tab 3. When the first tab 3 and the first electrode terminal 12 are welded, the first soldering 4 formed by toothless welding can reduce the stress of the second welding on the first tab 3, thereby reducing the damage to the first tab 3 during the second welding.

[0049] The toothless welding is welding using a nearly toothless welding head, the depth of the teeth of the nearly toothless welding head is relatively shallow, and a relatively shallow concave point is formed in the welding area after the welding is completed.

[0050] Optionally, the second welding mark 5 comprises a first welding area and a second welding area, the second welding area is arranged on the outer side of the first welding area in the circumferential direction, the first welding area is provided with a plurality of square welding marks, and the second welding area is provided with a plurality of circular welding marks.

[0051] The second welding mark 5 formed by welding the first tab part 3 and the electrode terminal comprises two different forms of welding areas, a first welding area and a second welding area located on the outer side of the first welding area in the circumferential direction. The first welding area has a plurality of square welding marks, and the depth of the square welding marks in the first welding area is relatively deep, so as to strengthen the connection strength between the first tab part 3 and the first electrode terminal 12; the second welding area has a plurality of circular welding marks, and the circular welding marks are located on the periphery of the second welding mark 5, which can relieve the stress between the second welding mark 5 and the first tab part 3 outside the second welding mark 5, and reduce the risk of tearing of the first tab part 3.

[0052] Optionally, with reference to Figure 3 , along the projection on the large surface of the first tab part 3, the projection area of the first welding mark 4 is S1, and the projection area of the second welding mark 5 is S2, and the following condition is met: 1≤S1 / S2≤10. That is, along the stacking direction of the second end 32 of the first tab part 3, the projection area of the first welding mark 4 is S1, and the projection area of the second welding mark 5 is S2. S1 / S2 can be 1, 1.3, 1.5, 1.8, 2.0, 2.2, 2.5, 2.8, 3.0, 3.2, 3.3, 3.5, 3.7, 4.0, 4.3, 4.5, 4.8, 5.0, 5.3, 5.6, 5.8, 6.0, 6.3, 6.5, 6.8, 7.2, 7.8, 8.0, 8.2, 8.6, 9.0, 9.3, 9.5, 9.8, 9.9 or 10, etc. After the first electrode assembly 2 and the first electrode terminal 12 are connected, in order to ensure sufficient overcurrent capacity and reduce the risk of tearing of the first tab part 3, the connection area between the first tab part 3 and the first electrode terminal 12 needs to meet the condition: 1≤S1 / S2≤10.

[0053] If the area ratio between the second welding mark 5 and the first welding mark 4 is too small, it means that the area of the second welding mark 5 is too small, the connection area between the first tab part 3 and the first electrode terminal 12 is small, and the overcurrent capacity is affected; if the area ratio between the second welding mark 5 and the first welding mark 4 is too large, the area of the second welding mark 5 is too large, the effect of the first welding mark 4 on relieving the stress of the first tab part 3 at the edge of the first welding mark 4 will be affected, and there may be a problem of tearing of the first tab part 3.

[0054] Optionally, the projection area of the first welding mark 4 meets the condition: 100mm2 ≤ S1 ≤ 2000 mm 2 The projected area of the second weld 5 satisfies: 20 mm 2 ≤ S2 ≤ 120 mm 2 .

[0055] The projected area S1 of the first weld 4 can be 100 mm 2 , 200 mm 2 , 300 mm 2 , 400 mm 2 , 500 mm 2 , 600 mm 2 , 700 mm 2 , 800 mm 2 , 900 mm 2 , 1000 mm 2 , 1100 mm 2 , 1200 mm 2 , 1300 mm 2 , 1400 mm 2 , 1500 mm 2 , 1600 mm 2 , 1700 mm 2 , 1800 mm 2 , 1900 mm 2 , or 2000 mm 2 , etc.

[0056] The projected area S2 of the second weld 5 can be 20 mm 2 , 25 mm 2 , 30 mm 2 , 35 mm 2 , 40 mm 2 , 45 mm 2 , 50 mm 2 , 55 mm 2 , 60 mm 2 , 65 mm 2 , 70 mm 2 , 75 mm 2 , 80 mm 2 , 85 mm 2 , 90 mm 2 , 95 mm 2 , 100 mm 2 , 105 mm 2 , 110 mm 2 , 115 mm 2 , or 120 mm 2 , etc.

[0057] Optionally, the first welding mark 4 has a first edge 41, the second welding mark 5 has a second edge 51, and the minimum distance between the first edge 41 and the second edge 51 is c, which satisfies: 0.5mm≤c≤10mm. The minimum distance c between the first edge 41 and the second edge 51 can be 0.5mm, 0.8mm, 1.0mm, 1.2mm, 1.4mm, 1.6mm, 1.8mm, 2.0mm, 2.2mm, 2.5mm, 2.7mm, 2.8mm, 3.0mm, 3.2mm, 3.5mm, 3.8mm, 4.0mm, 4.1mm, 4.3mm, 4.5mm, 4.8mm, 5.0mm, 5.2mm, 5.6mm, 5.8mm, 6.0mm, 6.3mm, 6.7mm, 7.0mm, 7.3mm, 7.8mm, 8.1mm, 8.4mm, 8.6mm, 8.9mm, 9.1mm, 9.4mm, 9.6mm, 9.8mm, or 10mm, etc.

[0058] In order to make the connection strength between the first tab part 3 and the first electrode terminal 12 sufficient and to alleviate the tearing of the first tab part 3, the minimum distance c between the first edge 41 and the second edge 51 should satisfy: 0.5mm≤c≤10mm. If the second edge 51 of the second welding mark 5 is too close to the first edge 41 of the first welding mark 4, a certain pressure effect will be generated on the part of the first tab part 3 outside the first welding mark 4 when the second torque welding is performed, which causes the part of the first tab part 3 outside the first welding mark 4 to be warped and further torn. If the second edge 51 of the second welding mark 5 is too far from the first edge 41 of the first welding mark 4, it indicates that the welding area between the first tab part 3 and the first electrode terminal 12 is too small, which affects the overcurrent capacity between the first electrode assembly 2 and the first electrode terminal 12.

[0059] Optionally, referring to Figure 5 and Figure 6 , the battery monomer further comprises a second electrode assembly 6 and a second tab part 7, both of which are arranged in the shell 1, the second tab part 7 comprises at least two second tab pieces, the second tab pieces extend from at least one end of the second electrode assembly 6, and the second tab part 7 is electrically connected to the first electrode terminal 12; the third welding mark 8 and the fourth welding mark 9 are arranged on the second tab part 7, along the projection on the large surface of the first tab part 3, the projection area of the first welding mark 4 is S1, along the projection on the large surface of the second tab part 7, the projection area of the third welding mark 8 is S3, and the sum of the projection area of the second welding mark 5 and the projection area of the fourth welding mark 9 is S4, which satisfies: S1+S3>S4.

[0060] The second lug portion 7 has a third end 71 and a fourth end 72, the plurality of third ends 71 are connected with the second electrode assembly 6, and the fourth end 72 is stacked and welded to form a third welding mark 8, and the third welding mark 8 is connected with the first electrode terminal 12 to form a fourth welding mark 9. The projection direction along the large surface of the first lug portion 3 is the same as the projection direction along the large surface of the second lug portion 7.

[0061] The first lug portion 3 of the first electrode assembly 2 is pre-welded to form a first welding mark 4, and the second lug portion 7 of the second electrode assembly 6 is pre-welded to form a third welding mark 8, and then the first electrode terminal 12 is welded with the first lug portion 3 in the first welding mark 4 area to form a second welding mark 5, and the first electrode terminal 12 is welded with the second lug portion 7 in the third welding mark 8 area to form a fourth welding mark 9. That is, the first lug portion 3 of the first electrode assembly 2 and the second lug portion 7 of the second electrode assembly 6 are welded with different areas of the first electrode terminal 12 respectively. Compared with stacking the first lug portion 3 and the second lug portion 7, welding the first lug portion 3 and the second lug portion 7 with different areas of the first electrode terminal 12 respectively can reduce the connection thickness between the first lug portion 3 and the second lug portion 7, thereby reducing the virtual welding between the first lug portion 3, the second lug portion 7 and the first electrode terminal 12.

[0062] In addition, the area of the first welding mark 4 formed after the first lug portion 3 is pre-welded should be greater than the area of the second welding mark 5 formed after the first lug portion 3 is welded with the first electrode terminal 12, that is, the second welding mark 5 is in the first welding mark 4 area; the area of the third welding mark 8 formed after the second lug portion 7 is pre-welded should be greater than the area of the fourth welding mark 9 formed after the second lug portion 7 is welded with the plurality of first electrode terminals 12, that is, the fourth welding mark 9 is in the third welding mark 8 area. That is, the sum of the projection area of the first welding mark 4 and the projection area of the third welding mark 8 is greater than the sum of the area of the second welding mark 5 and the projection area of the fourth welding mark 9, so as to satisfy the connection strength between the first lug portion 3, the second lug portion 7 and the first electrode terminal 12, and at the same time, alleviate the problem of bulging or tearing of the first lug portion 2 outside the first welding mark 4 and the second lug portion 7 outside the third welding mark 8.

[0063] Specifically, the first lug portion 3 is pre-welded to form a first welding mark 4, and the second lug portion 7 is pre-welded to form a third welding mark 8, and then the first lug portion 3 and the second lug portion 7 are spliced, that is, the first welding mark 4 and the third welding mark 8 do not overlap, and then the first lug portion 3 and the second lug portion 7 are welded with the first electrode terminal 12, and the second welding mark 5 formed by welding the first lug portion 3 with the first electrode terminal 12 and the fourth welding mark 9 formed by welding the second lug portion 7 with the second electrode terminal can be spaced apart or connected.

[0064] In an optional embodiment, the second end 32 of the first tab 3 is pre-welded to form a first weld 4, the third end 72 of the second tab 7 is pre-welded to form a third weld 8, the first weld 4 and the third weld 8 are rectangular, and then the first tab 3 and the second tab 7 are welded to the first electrode terminal 12 to form a second weld 5 and a fourth weld 9 respectively, the second weld 5 and the fourth weld 9 together form a circular weld, thereby realizing the welding of the first tab 3 and the second tab 7 to the first electrode terminal 12.

[0065] Optionally, the roughness of the second weld 5 is a1, the roughness of the first weld 4 is a2, the roughness of the fourth weld 9 is d1, and the roughness of the third weld 8 is d2, and the following conditions are met: 5≤a1 / a2≤280, 5≤d1 / d2≤280.

[0066] Wherein, a1 / a2 can be 5, 10, 15, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250, 260, 270, 275 or 280, etc.

[0067] d1 / d2 can be 10, 15, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250, 260, 270, 275 or 280, etc.

[0068] Since the first tab 3 and the second tab 7 are pre-welded and then spliced and welded to the first electrode terminal 12 without overlapping, the thickness of the first tab 3 and the second tab 7 welded to the first electrode terminal 12 is relatively small, the first tab 3 and the second tab 7 can be easily welded to the first electrode terminal 12 and achieve sufficient welding strength, and therefore the roughness of the second weld 5 and the fourth weld 9 can be relatively reduced.

[0069] Optionally, the roughness of the second weld 5 satisfies: 300μm≤a1≤2800μm; the roughness of the first weld 4 satisfies: 10μm≤a2≤500μm; the roughness of the fourth weld 9 satisfies: 300μm≤d1≤2800μm; the roughness of the third weld 8 satisfies: 10μm≤d2≤500μm, etc.

[0070] The roughness a1 of the second weld 5 can be 300μm 、 400μm 、500 pm, 600 pm, 700 pm, 800 pm, 1000 pm, 1100 pm, 1200 pm, 1300 pm, 1400 pm, 1500 pm, 1600 pm, 1700 pm, 1800 pm, 1900 pm, 2000 pm, 2100 pm, 2200 pm, 2300 pm, 2400 pm, 2500 pm, 2600 pm, 2700 pm, 2750 pm, or 2800 pm, etc.

[0071] The roughness a2 of the first weld 4 can be 10 pm, 20 pm, 50 pm, 80 pm, 100 pm, 120 pm, 150 pm, 180 pm, 200 pm, 220 pm, 240 pm, 260 pm, 280 pm, 300 pm, 330 pm, 340 pm, 350 pm, 360 pm, 380 pm, 400 pm, 410 pm, 420 pm, 430 pm, 440 pm, 450 pm, 470 pm, 480 pm, 490 pm, or 500 pm, etc.

[0072] The roughness d1 of the third weld 8 can be 300 pm, 400 pm 、 500 pm, 600 pm, 700 pm, 800 pm, 1000 pm, 1100 pm, 1200 pm, 1300 pm, 1400 pm, 1500 pm, 1600 pm, 1700 pm, 1800 pm, 1900 pm, 2000 pm, 2100 pm, 2200 pm, 2300 pm, 2400 pm, 2500 pm, 2600 pm, 2700 pm, 2750 pm, or 2800 pm, etc.

[0073] The roughness d2 of the fourth weld 9 can be 10 pm, 20 pm, 50 pm, 80 pm, 100 pm, 120 pm, 150 pm, 180 pm, 200 pm, 220 pm, 240 pm, 260 pm, 280 pm, 300 pm, 330 pm, 340 pm, 350 pm, 360 pm, 380 pm, 400 pm, 410 pm, 420 pm, 430 pm, 440 pm, 450 pm, 470 pm, 480 pm, 490 pm, or 500 pm, etc.

[0074] Optionally, the following is satisfied: 0.9 < S1 / S3 < 1.1. Wherein, S1 / S3 can be 0.9, 0.91, 0.92, 0.93, 0.94, 0.95, 0.96, 0.97, 0.98, 0.99, 1.0, 1.01, 1.02, 1.03, 1.04, 1.05, 1.06, 1.07, 1.08, 1.09, or 1.1, etc.

[0075] The projection area of the first welding mark 4 formed after the first lug portion 3 is pre-welded is S1, and the projection area of the third welding mark 8 formed after the second lug portion 7 is pre-welded is S3. In order to meet the overcurrent requirement between the first electrode assembly 2 and the second electrode assembly 6 and the first electrode terminal 12, the projection area of the first welding mark 4 S1 and the projection area of the third welding mark 8 S3 should satisfy: 0.9≤S1 / S3≤1.1. Preferably, the projection area S1 of the first welding mark 4 and the projection area S3 of the third welding mark 8 are approximately equal.

[0076] Optionally, the first welding mark 4 is rectangular. The first welding mark 4 is configured to be rectangular to increase the connection area between the first lug portions 3, thereby reducing the gap between the plurality of first lug pieces, and further reducing the risk of tearing of the first lug portion 3.

[0077] Optionally, the second welding mark 5 is circular. The first lug portion 3 and the first electrode terminal 12 are welded to form the second welding mark 5. Since the first lug portion 3 at the edge of the first welding mark 4 is thinned by the first welding mark 4 and the strength is reduced, when the second welding mark 5 is circular, the edge of the circular second welding mark 5 is round, reducing the stress on the first lug portion 3 at the edge of the first welding mark 4, thereby reducing the risk of tearing of the first lug portion 3.

[0078] Optionally, along the projection on the large surface of the first lug portion 3, the area of the second welding mark 5 is S2, and the end surface area of the end of the first lug portion 3 connected with the electrode terminal is S5, satisfying: 0.25≤S2 / S5≤0.95. That is, along the stacking direction of the second end 32 of the first lug portion 3, the area of the second welding mark 5 is S2, and the end surface area of the end of the first lug portion 3 connected with the electrode terminal is S5. Wherein, S2 / S5 can be 0.25, 0.28, 0.3, 0.32, 0.33, 0.35, 0.36, 0.38, 0.4, 0.42, 0.45, 0.47, 0.49, 0.51, 0.53, 0.56, 0.58, 0.6, 0.65, 0.68, 0.7, 0.72, 0.74, 0.76, 0.78, 0.8, 0.83, 0.86, 0.88, 0.9, 0.91, 0.93, 0.94 or 0.95, etc. The area of the second welding mark 5 should be sufficient to provide sufficient overcurrent capacity between the first electrode assembly 2 and the first electrode terminal 12, therefore, it is necessary to satisfy: 0.25≤S2 / S5≤0.95.

[0079] Optionally, the area of the second welding mark 5 satisfies: 20mm 2 ≤S2≤120mm 2 ; the end surface area of the end of the first lug portion 3 connected with the electrode terminal satisfies: 50mm 2 ≤S5≤300mm 2 .

[0080] The projected area S2 of the second weld 5 can be 20 mm 2 , 25 mm 2 , 30 mm 2 , 35 mm 2 , 40 mm 2 , 45 mm 2 , 50 mm 2 , 55 mm 2 , 60 mm 2 , 65 mm 2 , 70 mm 2 , 75 mm 2 , 80 mm 2 , 85 mm 2 , 90 mm 2 , 95 mm 2 , 100 mm 2 , 105 mm 2 , 110 mm 2 , 115 mm 2 , or 120 mm 2 or more.

[0081] The end surface area S5 of the end of the electrode terminal connected to the first tab portion 3 can be 50 mm 2 , 55 mm 2 , 60 mm 2 , 65 mm 2 , 70 mm 2 , 75 mm 2 , 80 mm 2 , 85 mm 2 , 90 mm 2 , 95 mm 2 , 100 mm 2 , 105 mm 2 , 110 mm 2 , 115 mm 2 , 120 mm 2 , 140 mm 2 , 160 mm 2 , 180 mm 2 , 200 mm 2 , 210 mm 2 , 220 mm 2 , 230 mm 2 , 240 mm 2 , 250 mm 2 , 260 mm 2 , 270 mm 2 , 280 mm 2 , 290 mm 2 , or 300 mm 2etc.

[0082] The application also provides a battery cell, referring to Figure 4 The battery cell comprises a housing 1, a first electrode terminal 12, a first electrode assembly 2, a first tab 3, a second electrode assembly 6 and a second tab 7, the housing 1 is used to accommodate the first electrode assembly 2 and the second electrode assembly 6, the housing 1 has a first wall 11; the first electrode terminal 12 is arranged on the first wall 11; the first tab 3 comprises at least two first tab pieces, the first tab pieces extend from at least one end of the first electrode assembly 2, the first tab 3 is electrically connected to the first electrode terminal 12; the second tab 7 comprises at least two second tab pieces, the second tab pieces extend from at least one end of the second electrode assembly 6, the second tab 3 is electrically connected to the first electrode terminal 12; the first tab 3 and the second tab 7 are overlapped and welded to form a first weld 4 and a second weld 5, along the projection on the large surface of the first tab 3 or the second tab 7, the orthographic projection of the second weld 5 falls into the orthographic projection of the first weld 4, the second weld 5 is used to weld at least one of the first tab 3 and the second tab 7 with the first electrode terminal 12; wherein the roughness of the second weld 5 is greater than the roughness of the first weld 4.

[0083] The first tab 3 extends from the end of the first electrode assembly 2 and is electrically connected to the first electrode terminal 12, the first electrode assembly 2 and the first tab 3 are arranged in the housing 1, the first tab 3 has a first end 31 and a second end 32, the first end 31 of the first tab 3 is connected to the first electrode assembly 2; the second tab 7 extends from the end of the second electrode assembly 6 and is electrically connected to the first electrode terminal 12, the second electrode assembly 6 and the second tab 7 are arranged in the housing 1, the second tab 7 has a third end 71 and a fourth end 72, the third end 71 of the second tab 7 is connected to the second electrode assembly 6; the second end 32 of the first tab 3 and the fourth end 72 of the second tab 7 are overlapped and welded to form a first weld 4, the first weld 4 is used to press the first tab 3 and the second tab 7, the first weld 4 is connected to the first electrode terminal 12 to form a second weld 5, the second weld 5 is used to weld the first tab 3 and the first tab 3 with the first electrode terminal 12; along the overlapping direction of the second end 32 of the first tab 3 and the fourth end 72 of the second tab 7, the projection of the second weld 5 falls into the projection of the first weld 4, the roughness of the second weld 5 is greater than the roughness of the first weld 4.

[0084] In the battery cell provided by the embodiments of the present application, when the first electrode assembly 2 and the second electrode assembly 6 are connected to the first electrode terminal 12, first, the first end 31 of the first tab 3 is connected to the first electrode assembly 2, and the third end 71 of the second tab 7 is connected to the second electrode assembly 6, then the second end 32 of the first tab 3 and the fourth end 72 of the second tab 7 are overlapped and pre-welded to form the first welding mark 4, and then the overlapped first tab 3 and second tab 7 are welded to the first electrode terminal 12 in the area of the first welding mark 4 to form the second welding mark 5. Since the thickness of the overlapped first tab 3 and second tab 7 is relatively thick, in order to prevent the first tab 3 and the second tab 7 from being loosely welded to the first electrode terminal 12, the depth of the second welding mark 5 needs to be increased, that is, the roughness of the second welding mark 5 needs to be increased, so that the first tab 3 and the second tab 7 are in sufficient contact with the first electrode terminal 12, thereby improving the connection strength between the first tab 3, the second tab 7 and the first electrode terminal 12.

[0085] Optionally, the roughness of the second welding mark 5 is a1, and the roughness of the first welding mark 4 is a2, and 6≤a1 / a2≤300 is satisfied. Wherein a1 / a2 can be 6, 10, 15, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250, 260, 270, 280, 290 or 300, etc. The roughness of the second welding mark 5 is greater than the roughness of the first welding mark 4, which reduces the problem of loose welding between the first tab 3 and the first electrode terminal 12, so as to improve the welding between the first tab 3 and the first electrode terminal 12.

[0086] Optionally, the roughness of the second welding mark 5 satisfies 280μm≤a1≤3000μm, and the roughness of the first welding mark 4 satisfies 10μm≤a2≤500μm.

[0087] The roughness a1 of the second welding mark 5 can be 280μm, 300μm, 400μm 、 500μm, 600μm, 700μm, 800μm, 1000μm, 1100μm, 1200μm, 1300μm, 1400μm, 1500μm, 1600μm, 1700μm, 1800μm, 1900μm, 2000μm, 2100μm, 2200μm, 2300μm, 2400μm, 2500μm, 2600μm, 2700μm, 2800μm, 2900μm or 3000μm, etc.

[0088] The roughness a2 of the first welding mark 4 can be 10 μm, 20 μm, 50 μm, 80 μm, 100 μm, 120 μm, 150 μm, 180 μm, 200 μm, 220 μm, 240 μm, 260 μm, 280 μm, 300 μm, 330 μm, 340 μm, 350 μm, 360 μm, 380 μm, 400 μm, 410 μm, 420 μm, 430 μm, 440 μm, 450 μm, 470 μm, 480 μm, 490 μm, or 500 μm, etc.

[0089] Specifically, since the thickness of the first tab portion 3 and the second tab portion 7 after being stacked is thick, in order to prevent the first tab portion 3 and the second tab portion 7 from being falsely welded with the first electrode terminal 12, it is necessary to increase the roughness of the second welding mark 5 so that the first tab portion 3 and the second tab portion 7 are in sufficient contact with the first electrode terminal 12. However, if the roughness of the second welding mark 5 is too large, the second welding mark 5 is prone to weld through the first tab portion 3 and the second tab portion 7.

[0090] The battery pack provided in the embodiments of the present application first pre-welds the first tab portion 3 to form the first welding mark 4, and then welds the first tab portion 3 and the first electrode terminal 12 in the area of the first welding mark 4 to form the second welding mark 5, thereby reducing the probability of the first tab portion 3 being warped or torn outside the area of the first welding mark 4. The roughness of the first welding mark 4 is smaller than that of the second welding mark 5, so that the first tab portion 3 is in sufficient contact with the first electrode terminal 12, the connection strength between the first tab portion 3 and the first electrode terminal 12 is improved, and the structural stability of the battery pack is further improved.

[0091] The battery pack provided in the embodiments of the present application first pre-welds the first tab portion 3 to form the first welding mark 4, and then welds the first tab portion 3 and the first electrode terminal 12 in the area of the first welding mark 4 to form the second welding mark 5, thereby reducing the probability of the first tab portion 3 being warped or torn outside the area of the first welding mark 4. The roughness of the first welding mark 4 is smaller than that of the second welding mark 5, so that the first tab portion 3 is in sufficient contact with the first electrode terminal 12, the connection strength between the first tab portion 3 and the first electrode terminal 12 is improved, and the structural stability of the battery pack is further improved.

[0092] It should also be noted that the terms "comprising", "comprises" or other variations thereof are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but can also include other elements not expressly listed or inherent to such process, method, article, or apparatus.

[0093] Various embodiments in the present specification are described in progressive manner, and the same or similar parts between various embodiments can be mutually referred to, and each embodiment focuses on the difference from other embodiments. In particular, for system embodiments, since they are basically similar to the method embodiments, the description is relatively simple, and the relevant parts can be referred to the part of the description of the method embodiments.

[0094] The above only describes the embodiments of the present application and is not intended to limit the present application. The present application can have various modifications and changes for those skilled in the art. Any modification, equivalent replacement, improvement, etc. within the spirit and principle of the present application shall be included in the scope of claims of the present application.

[0095] Although the embodiments of the present application are described in conjunction with the drawings, various modifications and changes can be made by those skilled in the art without departing from the spirit and scope of the present application, and such modifications and changes fall within the scope defined by the appended claims.

Claims

1. A battery cell, characterized by, The application relates to a battery electrode terminal structure, comprising: a shell for accommodating a first electrode assembly, the shell having a first wall; a first electrode terminal arranged on the first wall; a first electrode assembly and a first tab part, the first tab part comprising at least two first tab pieces extending from at least one end of the first electrode assembly, the first tab part being electrically connected to the first electrode terminal; a first solder mark and a second solder mark are arranged on the first tab part, along a projection on a large surface of the first tab part, a normal projection of the second solder mark falls within a normal projection of the first solder mark, the second solder mark is used for soldering the first electrode terminal and the first tab part, and the second solder mark is circular; wherein a roughness of the second solder mark is greater than a roughness of the first solder mark, the roughness of the second solder mark is a1, the roughness of the first solder mark is a2, and 5<=a1 / a2<=300 is satisfied; along the projection on the large surface of the first tab part, an area of the second solder mark is S2, and an end surface area of an end of the electrode terminal connected to the first tab part is S5, and 0.25<=S2 / S5<=0.95 is satisfied; along the projection on the large surface of the first tab part, a projection area of the first solder mark is S1, and a projection area of the second solder mark is S2, and 1<S1 / S2<=10 is satisfied.

2. The battery cell of claim 1, wherein, The roughness of the second solder mark satisfies 300 mu m<=a1<=3000 mu m, and the roughness of the first solder mark satisfies 10 mu m<=a2<=500 mu m.

3. The battery cell of claim 1, wherein, The first solder mark is formed by toothless soldering.

4. The battery cell of claim 1, wherein, The second solder mark comprises a first soldering area and a second soldering area, the second soldering area is arranged on a circumferential outer side of the first soldering area, a plurality of square solder marks are arranged in the first soldering area, and a plurality of circular solder marks are arranged in the second soldering area.

5. The battery cell of claim 1, wherein, The projection area of the first welding mark satisfies: 100mm 2 ≤ S1 ≤ 2000mm 2 The projection area of the second welding mark satisfies: 20mm 2 ≤ S2 ≤ 120mm 2 .

6. The battery cell of claim 1, wherein, The first solder mark has a first edge, the second solder mark has a second edge, and the minimum distance between the first edge and the second edge is c, and 0.5 mm<=c<=10 mm is satisfied.

7. The battery cell of claim 1, wherein, The first solder mark is rectangular.

8. The battery cell of claim 1, wherein, The area of the second welding bead satisfies: 20mm 2 ≤ S2 ≤ 120mm 2 The area of the end surface of the end of the electrode terminal connected with the first tab portion satisfies: 50mm 2 ≤ S5 ≤ 300mm 2 .

9. A battery cell characterized by, The application relates to a battery electrode terminal structure, comprising: a shell for accommodating a first electrode assembly and a second electrode assembly, the shell having a first wall; a first electrode terminal arranged on the first wall; a first electrode assembly and a first tab part, the first tab part comprising at least two first tab pieces extending from at least one end of the first electrode assembly, the first tab part being electrically connected to the first electrode terminal; a second electrode assembly and a second tab part, the second tab part comprising at least two second tab pieces extending from at least one end of the second electrode assembly, the second tab part being electrically connected to the first electrode terminal; the first tab part and the second tab part are overlapped and soldered to form a first solder mark and a second solder mark, along a projection on a large surface of the first tab part or the second tab part, a normal projection of the second solder mark falls within a normal projection of the first solder mark, the second solder mark is used for soldering at least one of the first tab part and the second tab part and the first electrode terminal, and the second solder mark is circular; The roughness of the second welding mark is greater than the roughness of the first welding mark, the roughness of the second welding mark is a1, the roughness of the first welding mark is a2, and 6≤a1 / a2≤300 is satisfied; The area of the second welding mark along the projection on the large surface of the first tab part is S2, and the area of the end face of the end of the electrode terminal connected with the first tab part and the second tab part is S5, and 0.25≤S2 / S5≤0.95 is satisfied; The projected area of the first welding mark along the projection on the large surface of the first tab part is S1, and the projected area of the second welding mark is S2, and 1 10. The battery cell of claim 9, wherein, The roughness of the second welding mark satisfies 280μm≤a1≤3000μm, and the roughness of the first welding mark satisfies 10μm≤a2≤500μm.

11. A battery pack, characterized by The battery cell includes the battery cell of any one of claims 1 to 10. The battery cell includes the battery cell of any one of claims 1 to 10.

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